1. Field of the Invention
The invention relates to a method for steering a roller vehicle by a roller mat and a support arrangement in compliance with a roller vehicle to be steered by a roller mat.
More particularly, the invention relates to a method to steer a roller vehicle by a roller mat, in which the vehicle has an essentially rigid body part for supporting the frame and a power engine 2 with transmission means 3 to transmit power to the roller mat which is at least partially curved to form a turnable roller mat 4, such that one side of the roller mat is shortened and the other side thereof is correspondingly lengthened. The support arrangement to steer the vehicle to a curved form includes the turnable roller mat 4, and the rigid body part 1 supports the power engine 2 above and the transmission means 3 transmits a driving force directly to the outer periphery of the roller mat 4 adapted around a turnable roller wheel assembly 6, 7 under the body part 1.
In before-known roller-steered vehicles it has been used two individually driven roller mats, whereby by changing their rotational direction or speed the steering of the vehicle is accomplished. The weakness in this arrangement consists of, however, the need of two separate steering systems and the complexity and susceptibility to damages of the steering system caused by it.
To eliminate such disadvantages connected with the traditional steering system. There is known a steering system and device for its implementation according to the Finnish Patent No. 46708. By the principle presented in this patent the vehicle is provided only by one roller mat arranged around, the front and rear end roller assemblies, one of which is driven by a proper transmission gear of a power engine, and which are turned essentially equally by partial turns and minimum turning radius. In this case the roller mat is forced to a curved position effecting the turning. Especially concerning the directional stability this kind of a steering system is not, however, satisfactory. Particularly to improve the directional stability there is proposed in the Finnish Patent No. 51922 a better steering system and a device to realize it. The principle of this patent is mainly characterized in that the portion of the roller mat on the side of the vehicle's front end with its end roller assembly is turned by essentially greater turning radii than the minimum turning radius of the vehicle with a higher angular velocity than the rear portion of the roller mat with its roller assembly and simultaneously the rear end roller assembly and the rear end of the roller mat are forced to function automatically without any adjustable steering devices.
Both above-mentioned patents with respect to a curved position turnable roller mats have the disadvantage, that the roller mat does not remain over the turning rollers. A solution to this problem has therefore been attempted to be solved by making on the center line of the roller mat, to the inner periphery of the mat, a projection profiled as a dovetail, to the web of which are supported on both sides a pair of rollers connected to the steering levers to turn in a way corresponding to the turning of the end roller assembly in order to prevent that the roller mat, influenced by great lateral forces resisting the turning and applied by the base to the roller mat, would not slide off over the end roller assembly, which would, if happened, make the vehicle completely unfit for driving and steering. In practical test drives a disadvantage has anyhow been observed, that the projection formed as a dovetail cannot alone reliably prevent displacement of the roller mat, which disadvantage is yet emphasized in curve driving, when it is strived to tilt the vehicle to the side of the inner curve, and also in hill driving, when it is necessary to steer the vehicle obliquely because of for example a natural obstacle or steepness of the hill. The before-known vehicle provided with a roller mat turning as a curve should therefore be driven by a particular driving style, whereby one should always try to keep the vehicle, if possible, in constant position regarding the surface of the terrain, which can be done, when the driver transfers his own center of gravity to different locations in the vehicle without tilting the vehicle.
One purpose of the present invention is to eliminate the aforementioned disadvantages and weaknesses connected with the traditional roller mat steering, and on the other hand to provide a new method and device for steering of a roller device by a roller mat, so that the steering of the roller device would as accurately as possible resemble the steering principle of a motorcycle.
These purposes has been achieved by the method and arrangement mentioned in the introduction, the characteristic features of which have been presented in the enclosed claims.